Field of the Invention
The invention relates to a teat cup liner according to the preamble of claim 1 and to a vent suitable for such teat cup liner.
Description of Related Art
A generic teat cup liner is known, for example, from the patent family DE 10 2006 026 271 A1 and from the additional applications DE 10 2006 040 079 A1 and DE 10 2007 053 230 A1.
Each of these documents discloses a teat cup liner including a teat cup liner head which has an inserting opening for a teat. A hose part for receiving the teat is connected to the teat cup liner head. The teat cup liner head is configured to include a head sleeve which in the mounted state encompasses a teat cup the other end portion of which is adjacent to a tensioning bead of the hose part so as to apply tension to the teat cup liner.
The basic arrangement of such teat cup liner with respect to the teat cup is disclosed in the documents EP 1 119 235 B1 and EP 1 219 166 A2.
In the prior art cited in the beginning in the teat cup liner head an air inlet vent is formed via which an interior headspace is ventilated toward the atmosphere. Said ventilation ensures that no excessive vacuum is allowed to form in the teat cup liner head. The known advantages for the air inlet during milking at the teat cup liner are, inter alia, better milk transport and no back spraying from the manifold. Moreover, the desired vacuum relief is brought about by the combination with the animal-appropriate relief system developed by applicant in the massaging phase by the supplied air.
It is a problem with solutions of this type that the air inlet vent has a relatively small orifice diameter of about 0.6 to 1.0 mm. There is a risk of said vent orifice getting blocked during milking e.g. by the contact with the udder or with skin folds and stopping proper functioning. When using milking units of this kind, after each milking operation it has to be ensured that during usual cleaning of the teat cup liners also the air inlet vent is cleaned. This may be done, for example, manually by spray-washing or brushing the vent mouth.
DE 10 2008 027 277 A1 suggests a solution in which a flushing cap is attached to the teat cup liner head for cleaning a teat cup liner so that the interior headspace encompassed by the teat cup liner head as well as circumferential areas of the teat cup liner can be cleaned by a cleaning liquid.
In said document to applicant it is suggested to design the flushing cap to include a peripheral sealing lip for sealing the circumferential area of the teat cup liner to the outside so that the interior headspace and/or the respective outer circumferential portion of the teat cup liner head can be cleaned. With this solution the vent is positioned such that it is located in the space closed off by the sealing lip so that, when the teat cup liner is being cleaned, the vent is flushed and thus cleaned as well.
However, it turned out that the vent may also get blocked already during the milking operation so that before the afore-described flushing by the flushing cap manual cleaning has to be carried out to ensure the proper functioning of the milking unit. With the known teat cup liners the milker makes use of a type of nail in order to open the vent cross-section. This is relatively complicated to carry out during the milking operation and requires a lot of experience.